Dark data is the information your company collects but doesn’t use or manage....

https://wiki-club.win/index.php/Example_of_Tagging_Research_Files_with_ELN_Project_Codes:_Unlocking_Value_in_Life_Sciences_Data_Management

Dark data is the information your company collects but doesn’t use or manage. It often makes up 55% of data stored, leading to wasted storage and backup costs. Plus, it increases ransomware and breach risks since unmanaged data is harder to protect